1. Field of the Invention
The present invention relates to a method for producing a painted ceramic body. More specifically, it relates to a simplified method for producing a painted ceramic body which can be used as building materials such as art tiles, ceramic photographs, and the like.
2. Description of the Related Art
It has been expected that a painted ceramic body in which a black and white image or a color image is formed on a ceramic body such as a ceramic plate, would be used for various purposes, for example, not only for building materials such as art tiles used for walls of a bathroom or an entrance hall, but also for ceramic photographs such as portraits or funeral pictures, and accessories such as pendants or brooches. As a method for forming an image on the surface of a ceramic plate or the like, a method has conventionally been known, wherein after an image is formed on an ordinary photographic printing paper, a paper region of the photographic printing paper is removed and an image region is adhered to the surface of ceramic, and the surface of the image region is laminated with ultraviolet curing resin to allow protection of the image region. However, an image formed by this method does not have sufficient light resistance and heat resistance in an image region thereof. Accordingly, an image having excellent light resistance and heat resistance and which could be preserved semipermanently, would be advantageous in that the range of use for such ceramic bodies would be increased.
For example, Japanese Patent Application Laid-Open (JP-A) No. 2-252683 discloses a method in which a photosensitive film is adhered to the surface of ceramic and subjected to dot exposure through a color-separated lithographic film, and thereafter, this film is developed and the ceramic is calcined in such a manner that painting inorganic pigments for painting are sequentially placed thereon in accordance with a developed image. Further, JP-A No. 62-246887 discloses a method in which a photosensitive polymer is used in place of the above-described photosensitive film and directly applied onto ceramic and subjected to dot exposure, and thereafter, the polymer is subjected to development processing, and the ceramic is calcined with a pigment image formed thereon in such a manner as described above. Images (ceramic photographs) formed by the above-described methods each have extremely excellent preservability and can be semipermanently preserved. However, when the above-described methods are used, it is necessary to prepare a plurality of lithographic films into which a color image is separated for each color. Further, it is necessary to closely adjust an amount of the pigment when the pigment is applied to the surface of a developed photosensitive film. There are many cases in which the preparation of the film needs be repeatedly carried out due to poor reproducibility. Moreover, formation and calcination of each pigment layer need to be carried out repeatedly. Accordingly, the above-described methods each have a problem in that the operation is remarkably complicated and the production cost is high.
Furthermore, another method is also proposed, wherein printing using ink containing a painting pigment as a main component, is carried out on a transfer paper (a paper substrate on which a water-soluble polymer such as dextrin is coated) by screen printing or gravure printing, a cover coat resin (a hydrophobic polymer) is overcoated thereon, and the transfer paper is adhered to ceramic and calcined. An image formed by this method also has excellent durability and can be semipermanently preserved in the same manner as the above-described methods. However, in this case as well, it is necessary to prepare a plurality of lithographic films having the respective colors of the image and planographic printing plates, and formation and calcination of a pigment image need to be repeatedly carried out. Accordingly, this method also has the same problem as that of the above-described methods in that the operation is remarkably complicated and the manufacturing cost is high. Further, the painting pigment is apt to cause clogging of meshes of a screen, and meshes of the screen cannot be made sufficiently small. As a result, there exists a problem in that an image like a sharp photograph having an excellent resolution is difficult to reproduce.
In view of the conventional production methods involving complicated procedures and high costs, the inventor disclosed a production method which can be conducted readily and at low costs in JP-A No. 6-166298. This method comprises the steps of transferring a pigment image onto a thermally transferrable image receiving sheet for ceramics (“thermally transferrable film”) in accordance with image information using a thermally transferrable printer by which a thermally transferrable image donating sheet (ink sheet) having a hot melt image donating layer (ink layer) containing a painting pigment is used, adhering the sheet to a ceramic body, and sintering the ceramic body to thereby form a ceramic image on the ceramic body. This method made it possible to produce the painted ceramic body in a simple manner and at low costs since color images could directly be formed on an image receiving sheet or a transfer paper in accordance with the digital data without using the planographic printing plate and the lithographic film. This method, however, requires preparation of the image donating sheet, in which the image donating layer containing the painting inorganic pigment and a hot melt binder on a thin film has been coated, in the form of a roll (a state where a longitudinal sheet is rolled) beforehand, such that the inorganic pigment image can be transferred to an image receiving paper using a commercially available thermosensitive transferrable printer. Furthermore, in order to form an image containing two or more colors, this method requires preparation of the image donating sheet, on which respective color ink layers have been successively disposed, in the form of a roll. From the foregoing, the kinds of usable pigments are limited in view of the appointed date of delivery and costs.
Another method disclosed in JP-A No. 6-166298 has a drawback in that two or more kinds of pigments cause discoloration through co-melting to thus fail in color reproduction. In order to avoid such a phenomenon, the inventor disclosed a method which comprises placing pigments that possibly produce such a phenomenon onto separate thermally transferrable image receiving sheets for ceramics (“thermally transferrable film”), adhering the respective sheets to the ceramic body and sintering the ceramic body to thereby alleviate the degree of discoloration. However, this method also requires preparation of the image donating sheet, in which the image donating layer containing the painting inorganic pigment and a hot melt binder on a thin film has been coated, in the form of a roll (a state where a longitudinal sheet is rolled) beforehand, such that the inorganic pigment image can be transferred to a image receiving paper using a commercially available thermosensitive transferrable printer, and further, preparation of the image donating sheet beforehand, on which respective color image donating layers have been successively disposed, in the form of a roll. From the foregoing, the kinds of usable pigments are limited in view of the appointed date of delivery and costs.
Moreover, in order that an image having excellent preservability be formed on a ceramic body, it is necessary to sinter on a ceramic body an image comprised of an inorganic pigment, and also select an image forming method suitable for the characteristics of inorganic pigment.